The Protein Expression and Tetramer Core will produce and standardize several key reagents that will be required by the investigators in this Program Project. The specific aims of the core are: 1) To purify SLE prone mice; 2) to produce CD1d/alpha-galactosyl ceramide tetramers for the analysis of NK T cells in SLE prone mice; 3) to produce DWEYSVWLSN peptide tetramers that will be used for analysis and isolation of anti-dsDNA B cells. The core will be supervised by Drs. Davidson and Porcelli who will serve as Co-Directors, and will make extensive use of equipment that is already available and operation in their laboratories. Both Co-Directors are experienced in the production and purification of monoclonal antibodies and a variety of recombinant proteins. Dr. Davidson has extensive background experience in the production of fusion proteins using the adenovirus-based expression system that will be employed by the core. Dr. Porcelli's laboratory is experienced in the production of recombinant soluble CD1 proteins and is currently developing the methods for tetramer assembly. A technical assistant will be hired and trained by the Do-Directors to perform the routine production and quality control tasks of the core facility. The core will provide all of the investigators in the program with a stable source of high quality specialized protein reagents that will be applicable to a variety of studies proposed in each of the four projects of the program. The establishment of this core facility will allow the investigators to share expertise and to avoid duplication of effort in the production of these reagents. In addition, the core facility will maintain a high level of quality control and standardization of the reagents it produces.